In the context of rapidly expanding policy and practice, this systematic review collates and appraises evidence for the effectiveness of menstrual health interventions in the East Asia and Pacific region. Structured searches were undertaken in 7 databases and Google Scholar. Grey literature was identified through searching and survey of stakeholders. Quantitative evaluations were eligible. We audited the interventions and outcomes assessed in current evidence, undertook risk of bias assessment, and narrative synthesis of findings. The review protocol was registered prior to searching (PROSPERO: 343613). Eighteen studies were eligible; categorised according to the requirements for menstrual health they addressed. Information and education intervention studies (n = 11) found school-based programs improved menstrual knowledge test scores but did not evaluate impacts on broader outcomes. Evaluations of interventions providing materials, facilities, and services for menstruation (n = 4) focused on product acceptability. Studies exhibited a serious risk of bias without adequate controls, limitations in intervention allocation, adherence, and participant retention. Six studies of interventions to improve care for menstrual discomforts found decreased selfreported pain but had serious bias without placebo controls. Two interventions targeted the supportive social environment for menstruation. There is insufficient evidence for the effectiveness of menstrual health interventions in the East Asia and Pacific region. Future research must improve reporting, provide clear intervention theory of change, and improve measurement of core concepts. Evaluations of interventions that align with policy and practice are needed, facilitated by partnerships between researchers, government, and practitioners.